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Old 09-14-2011, 01:35 AM
Join Date: Jun 2000
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I want to make my own fireproof box

Just kinda an acedemic excersie more than anything, but I have a RL idea involving this.

What kind of insulation is used for making fireproof boxes and or small fireproof safes? Prefer something easily obtainable over the internet.
Old 09-14-2011, 02:07 AM
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Old 09-14-2011, 02:15 AM
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Originally Posted by Nametag View Post
Anything a little more on the lighter and high tech side? I'm sure good old concrete can do it, but its a little unweildy for my intended application. I'm thinking something like the size of a hefty hardbound book.
Old 09-14-2011, 02:26 AM
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Something the size of a book obviously isn't going to have the same kind of heat resistance as something the size of a safe - but you probably knew that.

If budget is no constraint, then you could buy some aerogel and embed that in something durable enough to keep it in place around your container. I'm guessing you probably don't want to spend thousands or millions on this, so...

How about epoxy generously loaded with glass microspheres? You can buy both of those materials from boatbuilding suppliers - the glass microspheres are normally used for thickening the epoxy and adding bulk, but they also happen to make it a good thermal insulator.

Last edited by Mangetout; 09-14-2011 at 02:26 AM.
Old 09-14-2011, 02:52 AM
Join Date: Feb 2011
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Aww I was going to say aerogel too. How about amorphous metal foam?
Old 09-14-2011, 03:19 AM
Join Date: Jul 2002
Location: UK
Posts: 4,887
Get some space shuttle tiles. You can hold one corner while the other is red-hot. There may actually be sources of this sort of silica material available.

What are you trying to protect - fireproof paper safes are not suitable for digital storage media, for example.

Also used on the Shuttle is Nomex (as used for racing drivers/firemen protective suits). Coupled with reflective insulation it may do the trick. That should be readily available.

Old 09-14-2011, 11:51 AM
Join Date: Dec 1999
Posts: 1,532
I know the OP wants to build his own, but is the cake worth the candle? You can readily purchase small "media safes" that will protect digital media from very high temperatures. I have one, about the size of an unabridged dictionary. Never having had a fire, can't completely guarantee it, but the specs indicate that it would perform its function easily.

Then the time you saved by not having to build one can be much better used in drinking beer, watching NASCAR on TV, and so forth.
Old 09-14-2011, 12:53 PM
Join Date: Jun 2000
Posts: 9,768
Originally Posted by Mangetout View Post
If budget is no constraint, then you could buy some aerogel and embed that in something durable enough to keep it in place around your container. I'm guessing you probably don't want to spend thousands or millions on this, so...
This may be the ticket in one of its many forms.

I am actually seeing sites where you can order blankets rated to resist like 1200degF not sure how long they last IN a fire but I can see where this stuff gets a little pricey for pet projects.

I was envisioning a type of "media safe" like a block of some kind of fire resistant foam with a pocket cut out to fit a hard drive or two. all this dicussion of backups here lately had me pondering..
Old 09-14-2011, 01:40 PM
Join Date: May 1999
Posts: 18,364
Don't some fire safes use drywall or gypsum board between the metal inner and outer shell?
Old 09-14-2011, 02:24 PM
Join Date: Dec 2006
Location: Edmonton, Alberta, Canada
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Here is a cheap, fast and easy way:

Get or make a metal box - ammo cases work great -if you have military surplus stores in the area, you can often find them there for $10-15, put your stuff in this box.
Get or make another metal box, that the first one will fit inside, with 2-3 inches of clearance top, bottom and all sides, the thicker the metal, the better.
get some chicken wire/stucco wire and loosely "crumple" it into the bottom of your bigger box, around 2 inches thick
Place your smaller box centered on the crumpled wire, and crumple more chicken wire or stuco wire to fill the open space around it, level to top of your smaller box (about 2 inches or so from top of big box)
Cut a sheet of drywall to fit inside bigger box on top of smaller box. fill remaining space with crumpled chicken wire.
Close lid.

This is based on a design that was used in WW2, during the bombing of London, to keep documents safe, incase of fire. It apparently worked quite well, but my googlefu did not allow me to find a reference to it. My childhood neighbour was a war bride, and she showed us her birth certificate and other documents that had survived in a box like this, even though the house it was in was burnt to ashes. They had obviously been heated, but were still flexible and readable.
"Outside of a dog, a book is man's best friend - inside of a dog- its too dark to read!" - Grouch Marx

Last edited by Full Metal Lotus; 09-14-2011 at 02:26 PM.
Old 09-15-2011, 01:08 AM
Join Date: Apr 2011
Posts: 1,767
better to fire-proof an existing safe. work on the inside. make a double-wall arangement on the sides, back, bottom, and ceiling with thick cement boards (easy to cut and snap to size.) between that and the metal, fill it with concrete. better to use crushed basalt sand (very heat resistant.) then just paint the cement board interior.
Old 09-15-2011, 02:33 AM
Join Date: Nov 2001
Location: Madison, WI
Posts: 36,997
I misunderstood the OP. So it's the contents of the box you want to protect! Well, that's completely different.
Old 09-15-2011, 08:44 AM
Join Date: Feb 2007
Location: Challenger Deep
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ISTR that flight data recorders are shrouded in a layer of phase-change material. When exposed to high temps, that material can absorb massive amounts of heat by melting (the phase-change); the interior of the enclosure never rises above the melting point of the material until the materal has all melted away.

One lesson from that is that nothing is permanently fireproof; your goal is to buy time, to keep the interior temperature below a design limit long enough for you/firefighters to put the fire out.

I recently bought a fire-resistant home safe. For security, it includes provisions for bolting it to a solid surface. That required drilling a couple of bolt holes thorugh the bottom of it. When doing so, I discovered that the interstice was filled with a peculiar waxy semi-fibrous material. I assume this was designed to function in a way similiar to the aforementioned FDR protection. As for exactly what it was, I couldn't say.

Academic exercises are fine and good fun, but if you're serious about protecting valuables (like data-filled hard drives/CD's/DVD's), you may not want to take a chance on prototype fire protection. Fire-resistant boxes (portable, not at all the same as a boltable security safe) are available pretty cheap; example, this one buys you a half-hour of fire time for $26. An alternive would be offsite backup: store your backup media at your place of work, or at a friend's house. No fire safe needed then, as it's exceedingly unlikely for your home and the offsite storage location to burn up at exactly the same time.

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